I take a stimulant (not concerta), and it doesn't interfere with my socializing. In fact, it makes me better at socializing because I don't try to speedrun infodumping anymore. While it is, admittedly, less fun that I don't eventually end up blabbing about tsunami physics because somebody asked me whether I thought the Bluetooth keyboard was going dead, it means that there's more actual conversation that happens between myself and others.
That said, my kids both take stimulants. I've observed that it effects everyone a little differently, so, I dunno, maybe it is the concerta doing it.